A submarine optical divider has been used to divide a wavelength-multiplexed optical signal in a submarine optical transmission line. For example, a submarine optical divider is composed of components as shown in FIG. 1. In this submarine optical divider [prior art 1] optical path switching information is carried on a main signal of light input 1, then converted into an electrical signal by an O/E converter in the submarine optical divider, thereafter decoded by a decoder. By using the optical path switching information to be decoded, an optical switch 1 is switched.
Also, U.S. Pat. No. 5,170,273 discloses a wavelength-division switching system for optical frequency-shift keying signals [prior art 2], whose technical field is close to that of the invention, where E/O converters and O/E converters are used.
Further, Japanese patent application laid-open No. 6-224850 (1994) discloses an optical switch control system [prior art 3] where only necessary information is input through a wavelength filter to an optical switch controller so as to switch a transmission line by an optical control signal. This is technically close to the invention only as to controlling of optical switch.
However, when optical path switching information is carried on a main signal, as disclosed in prior arts 1 and 2, O/E converters and E/O converters need to-be provided in the device. Therefore, the volume of the entire submarine optical divider is so much increased. The increased volume of the submarine-optical divider causes a difficulty in handling, such as laying of device.